The present invention relates to a swash plate compressor.
JP-A-10-54350 discloses a conventional swash plate compressor. The swash plate compressor includes a housing composed of a front housing, a cylinder block and a rear housing, and the housing defines a plurality of cylinder bores, a suction chamber, a discharge chamber and a crank chamber therein. The front housing rotatably supports in the crank chamber a drive shaft, one end of which is exposed from the front housing. In the crank chamber, a swash plate is supported by the drive shaft so as to vary its inclination angle. Pistons are reciprocatingly received in the respective cylinder bores. Pairs of front and rear shoes are provided between the swash plate and the respective pistons for converting wobbling of the swash plate into reciprocation of the respective pistons. A supply passage provides communication between the discharge chamber and the crank chamber, and a capacity control valve is provided on the supply passage to regulate pressure in the crank chamber.
Also, with the swash plate compressor, the drive shaft is formed with a release passage, which communicates the crank chamber to the suction chamber. The release passage includes a first radial hole extending radially and an outflow hole extending axially and communicating the first radial hole to the suction chamber.
Further, with the swash plate compressor, a valve mechanism is provided on the drive shaft. The valve mechanism decreases opening degree of the release passage as the drive shaft is increased in rotating speed, and increases opening degree of the release passage as the drive shaft is decreased in rotating speed.
The swash plate compressor together with a condenser, an expansion valve, and an evaporator constitutes a refrigerating circuit, and the refrigerating circuit is used in air-conditioning apparatus for a vehicle. With the swash plate compressor, the capacity control valve adjusts pressure in the crank chamber on the basis of pressure in the suction chamber or a flow rate of refrigerating gas to change an angle of the swash plate with respect to the drive shaft to thereby change a discharge capacity of the compressor.
Also, with the swash plate compressor, while a vehicle is running at high speed, the release passage is decreased in opening degree as the drive shaft is increased in rotating speed, so that, in particular, when the compressor is put in a state of rotating at high speed with a large discharge capacity, reduction in compression load can be achieved by gradually increasing pressure in the crank chamber to decrease the discharge capacity. Conversely, with the swash plate compressor, while a vehicle is running at low speed, the release passage is increased in opening degree as the drive shaft is decreased in rotating speed, so that a desired refrigerating capacity can be achieved by gradually decreasing pressure in the crank chamber to increase the discharge capacity.
With a swash plate compressor, when a drive shaft is rotated at high speed, an improvement in sliding characteristic is required in sliding portions such as between cylinder bores and pistons, between a swash plate and respective shoes, and so on. Also, when a drive shaft is rotated at low speed, lubricating oil discharged with refrigerating gas to an external refrigerating circuit outside a swash plate compressor is demanded of reduction in quantity for achieving a high refrigerating capacity.